Recently, there are individual identification systems for identifying individuals by extracting biometric features peculiar to a human body such as an iris of an eye, a finger print, or a handprint and by performing a prescribed matching process based on the extracted results.
In addition, in recent years, human walking movements itself have been focused on as one biometric feature peculiar to a human body For example, there is an individual identification system for identifying individuals based on extracted results obtained by extracting biometrics features through a frequency analysis on acoustic oscillation (sound) generated by walking movements.
This individual identification system requires a microphone (acoustic to electric transducer) to be placed on a human body to detect a walking cycle using, as an index for one step, a subset of electric signals obtained by collecting acoustic oscillation energy during his/her walking movements through the microphone. The subset of signals representing acoustic oscillation at a moment of a foot landing generated by an impact caused when one foot part lands on the ground is gathered and then a system is used to extract features of a gait waveform peculiar to the body based on the detected results. (See, US Patent Publication US2002/0107649A1 (e.g., FIGS. 6 and 7), the entire contents of which being incorporated herein by reference.)
However, in this individual identification system, the acoustic oscillation at the point of landing varies according to the part of the body on which the microphone is placed. In addition, the electrical part representing the oscillation at landing cannot be accurately specified due to major influences from acoustic and electrical noise around the microphone, and accordingly it is difficult to precisely extract features of the gait waveform.